The present application relates to anti-lock braking systems and, more particularly, to hydraulic modulator systems for anti-lock braking systems.
Anti-lock braking systems are used in vehicles to prevent one or more wheels from locking during the application of braking force, thereby allowing a driver to maintain control of the vehicle. A typical anti-lock braking system includes wheel speed sensors, an electronic control unit (“ECU”) and a valve body such as a hydraulic control unit (“HCU”). The ECU is integrated with the HCU to form a hydraulic modulator or electro-hydraulic control unit (“EHCU”).
The HCU may include a motor for pumping hydraulic fluid, accumulators for storing accumulated hydraulic fluid and valves having valve stems for directing hydraulic fluid to the brakes. The ECU may include a processor for receiving signals from the speed sensors and solenoid coils corresponding to each valve stem for actuating the valves according to command signals generated by the processor. The ECU may be integrated with the HCU such that the coils contact the valve stems, thereby forming the EHCU.
The ECU may monitor the rotation of the wheels based on signals from the speed sensors. When a wheel is identified as rotating at a different speed than the other wheels, the ECU signals the coils to actuate the appropriate valves, thereby controlling the braking force applied to the identified wheel.
EHCUs used on motorcycles and other smaller vehicles are typically adapted from passenger cars due to the high cost of developing customized systems. While these systems are able to meet the performance needs of these vehicles, they are not the most efficiently sized systems. Typical EHCUs have a motor extending from the HCU and mounted externally of the ECU, thereby occupying valuable space. Additional disadvantages of such configurations include the need to seal the motor separately to prevent damage from environmental factors, the requirement of an electrical connection between the motor and the ECU that is traditionally an external connection or a drilled passage through the HCU that occupies valuable space and the need to machine the aluminum body of the HCU on the face opposite the valves and ECU.
Accordingly, there is a need for a hydraulic modulator without the above-mentioned disadvantages that makes efficient use of space such that it may be used with motorcycles and other small vehicles in which space is a premium.